A photoelectrosolographic imaging method wherein an absorbent material is used

ABSTRACT

A migration imaging system having a migration imaging member comprising a softenable layer, migration material and an absorbent blotter member, which imaging member may be imaged by forming a latent image on said member, softening the softenable layer and removing residual materials by removing the absorbent blotter member.

United States Patent [191 Sankus, Jr. et al.

[ Aug. 21, 1973 PHOTOELECTROSOLOGRAPHIC IMAGING METHOD WHEREIN ANABSORBENT MATERIAL IS USED [75] inventors: Josenh G. Sankus, Jr.,Fairport,

N.Y.; Nicholas L. Petruzulla, Columbus, Ohio [52] US. Cl. 96/1 R, 96/1LY, 96/1.4, 96/1.5, 96/36, 96/48, 117/37 LE, 250/49.5 ZC [51] Int. Cl.G033 13/10, 603g 13/22 [58] Field of Search 96/1, 27, 36, 36.3, 96/1.2,1.3, 1.4, 48, 1 L; 117/37 LE [56] References Cited UNITED STATES PATENTS3,271,145 9/1966 Robinson 96/1 R 2,812,709 11/1957 Gundlach... 96/1 R3,272,626 9/1966 Shinn 96/1 R 2,543,051 Oughton et al. 96/1 R 3,679,4057/1972 Makind et a1 96/1.5 3,121,006 2/1964 Middleton et a1. 96/1.53,102,045 8/1963 Metcalfe et al 1 17/37 LE 3,247,007 4/1966 Oliphant117/37 LE 3,231,379 l/1966 Hoemer 96/36.3

3,343,956 9/1967 Wright 96/1 X 3,520,681 7/1890 Gotfe 2,892,709 6/1959Mayer 3,542,465 1 l/ 1970 Pundsack.

3,556,781 1/1971 Levy et al. 96/1 Primary Examiner-Roland E. Martin, Jr.Attorney-James J. Ralabate, David C. Petre and Roger W. Parkhurst [5 7]ABSTRACT A migration imaging system having a migration imaging membercomprising a softenable layer, migration material and an absorbentblotter member, which imaging member may be imaged by forming a latentimage on said member, softening the softenable layer and removingresidual materials by removing the absorbent blotter member.

78 Claims, 11 Drawing Figures PAIENIED Ills Z 1 i975 sum 1 or INVENTORSJOSEPH G. SANKUS JR. BYNICHO LAS LPETRUZZELLA ATTORNEY PATENIEBAHBZI msabrasives SHEET 3 BF 3 PHOTOELECTROSOLOGRAPHIC IMAGING METHOD WI-IEREINAN ABSORBENT MATERIAL IS USED BACKGROUND OF THE INVENTION This inventionrelates to a novel imaging system in which the recording material isselectively moved through a softenable medium under the influence ofelectrical forces.

Various methods of forming visible images in response to patterns oflights and shadows are well known. Recently, palpable, visible imageshave often been formed by means involving the electrical propertiesrather than the chemical properties of various photoconductivematerials. For example, a uniformly charged layer of photoconductivematerial is exposed to a pattern of light-and-shadows and the resultingelectrostatic latent image pattern is used to control the selectiveattraction or repulsion of a marking material onto the surface of thephotoconductive layer thereby forming one type of electrostatographicimage.

More recently, however, a migration imaging system capable of producinghigh quality images of high density, continuous tone, and highresolution has been developed. Such a migration imaging system isdisclosed in copending application Ser. No. 460,377, filed June 1, 1965,now US. Pat. No. 3,520,623]. In one embodiment of that system an imagingmember comprising a substrate layer with a layer of softenable materialoverlying the substrate and a third layer comprising photosensitiveparticles overlying the softenable layer, is imaged in the followingmanner: A latent image is formed on the member by suitable means, forexample, by uniformly electrostatically charging and exposing theuniformly charged member to a pattern of activating electromagneticradiation. The latently imaged member is then developed by exposing itto a solvent which dissolves only the softenable layer. Thephotosensitive particles of the the third layer which have been exposedto the radiation, migrate through the intermediate soft enable layer asit is softened, depositing on the substrate an image of migratedphotosensitive particles corresponding to the radiation pattern to whichthe member was exposed. Where the softening step is performed by simplywashing the member in a suitable solvent, the material of the softenablelayer along with unmigrated residual portions of the upper layercomprising photosensitive particles, are substantially completely washedaway by the liquid solvent. The migrated particle image upon thesubstrate may then be fixed to the substrate. For many photosensitiveparticles which are preferred for use in such a migration imagingsystem, the image produced is a negative of a positive original.However, positive-to-positive imaging may be accomplished by varyingimaging parameters and materials.

The basic imaging member used in the new migration imaging system istypically in one of three configurations: 1) a layered configurationcomprising a substrate, coated with a layer of softenable material, anda fracturable or particulate layer comprising photosen' sitive materialon or embedded at the upper surface of the softenable layer; 2) a binderstructure, in which the photosensitive particles are dispersed in thesoftenable layer'overcoating the substrate; or, 3) an over-coatedstructure, in which a substrate is overcoated with a layer of softenablematerial, followed by an overlayer comprising photosensitive particles,and a second overlayer of softenable material sandwiching the layercomprising photosensitive particles.

Softenable as used herein is intended to mean any material which can berendered more permeable thereby enabling particles to migrate throughits bulk. Conventionally, changing permeability is accomplished by heator solvent softening. Fracturable layer or material as used herein,means any layer or material which is capable of breaking up duringdevelopment, thereby permitting portions of said layer to migratetowards the substrate or to be otherwise removed.

There are other systems for forming the latent image, whereinnon-photosensitive or inert, fracturable layers or particulate materialmay be used to form said images, as described in copending applicationSer. No. 483,675, filed Aug. 30, 1965, now US. Pat. No. 3,656,990. Inthat application and copending application Ser. No. 725,676, filed May1, 1968, now abandoned as well as the present application, a variety ofmethods which may be used for imaging the migration imaging member aredisclosed.

Likewise, various means for developing latent images in the novelmigration imaging system are known. Typical developing means includesolvent washaway, as described above, solvent vapor softening, heatsoftening and combinations of these methods. In another mode ofdevelopment, if the softenable layer is at least partially left behindon the substrate, it has been found that the unmigrated fracturablematerial remaining on the imaging member after development may beadhesively stripped off to yield complementary positive and negativeimages, as disclosed for example, in copending application Ser. No.642,830, filed June 1, 1967.

In new and growing areas of technology such as migration imaging systemsuitable for use in the present invention, new methods, apparatus,compositions of matter, and articles of manufacture continue to be discovered for the application of the new technology in a new mode. Thepresent invention relates to a new and advantageous system for thedevelopment of latent images in such migration imaging systems.

SUMMARY OF THE INVENTION It is, therefore, an object of this inventionto provide a novel imaging system.

It is another object of this invention to provide a novel imaging systemwherein a photosensitive layer is selectively displaced in imageconfiguration.

It is a further object of the invention to provide a novel imagingmember. g

It is another object of this invention to provide a migration imagingsystem employing a more simple development system. i

It is yet another object of this inventionto provide a migration imagingsystem including a cleaner, neater, more efficient system for thedisposal of residual byproducts of development.

It is still a further object of this invention to, provide a migrationimaging system which is more suitable for automatic imaging apparatus.

The foregoing objects and others are accomplished in accordance withthis invention by a migration imaging system having a novel migrationimaging member comprising a softenable layer, migration material and anabsorbent blotter member, which imaging member may be imaged by forminga latent image on said member,

softening the softenable layer and removing residual materials byremoving the absorbent blotter member.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theinvention as well as other objects and further features thereofreference is made to the following detailed disclosure of the preferredembodiments of the invention taken in conjunction with the accompanyingdrawings thereof, wherein:

FIG. 1 shows cross-sectional views of typical embodiments of a migrationimaging member.

FIG. 2 shows a solvent applicator-blotter roller suitable for use in theadvantageous system of the present invention.

FIG. 3 illustrates a dual roller applicator-blotter system for use inthe present inventive system.

FIG. 4 illustrates a preferred embodiment of the present inventionwherein the advantageous solvent applicator-blotter roller is used inconjunction with a migration imaging member.

FIG. 5 is a partially schematic cross-sectional view of preferredembodiments of the novel imaging member.

FIG. 6 illustrates a preferred embodiment of the novel migration imagingmember in conjunction with a suitable roller applicator.

FIG. 7 illustrates the novel migration imaging member in cooperationwith a solvent spray applicator.

FIG. 8 illustrates the novel migration imaging member being used in thenovel migration imaging system including expo-sure through asubstantially transparent substrate of said imaging member.

FIG. 9 illustrates the novel migration imaging member being used in thenovel migration imaging system including exposure through thesubstantially transparent absorbent blotter layer of the imaging member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, animaging member suitable for use in a migration imaging system istypically a layered configuration 10 comprising a substrate 11 coatedwith a layer of softenable material 12. The substrate 1 1 is typicallyan integral part of the imaging member, giving the entire member supportand serving as the backing for the desired image. However, imagingmembers without integral substrates may be used to form migration imageson any suitable surface which takes the place of the illustratedsubstrate.

In FIG. 1(b) a fracturable or particulate layer 13 comprising amigration marking material is contiguous the upper surface of thesoftenable layer. In various embodiments, the marking material may becoated onto, slightly embedded in, or substantially embedded in thesoftenable material of layer 12 at the upper surface of that layer. InFIG. 1(a) particulate marking particles 13 are dispersed throughout thesoftenable layer 12 in a binder structure. Both of these imaging memberconfigurations are suitable for use in preferred embodiments of thepresent inventive system.

In FIG. 2, applicator-roller I4 is designed to apply liquid or vaporsolvent, or heat, which dissolves or softens the softenable layer indeveloping a migration imaging member. The roller applicator-blottersystem 14 includes means 15 for continuously supplying solvent or heatto the surface 16 of the roller which is porous to allow passage ofliquid or vapor solvent from the roller to the imaging member. Thesurface 16 of the roller preferably comprises a porous, absorbentmaterial designed to blot up the unmigrated portion of thephotosensitive particles and the residue of the softenable layer from amigration imaging member substantially simultaneously with theapplication of the solvent or heat. Ideally, a system of blotter,solvent, and imaging member materials so synergistically matched that anabsorbent system absorbs or totally assimilates the residual materials,is preferred.

In FIG. 3 a dual roller system 19 comprising applicator-roller 20 andblotter-roller 21 cooperatively connected by member 22 is illustrated asan embodiment of a system which performs essentially the same functionsas roller 14 shown in FIG. 2, but the dual roller system of FIG. 3provides for a lapse of time between application and blotting, in whichtime the applied solvent has a greater opportunity to act upon thesoftenable layer of the imaging member. In FIG. 3, the firstapplicator-roller 20 need not include the absorbent surface 18, which inthis embodiment, is included on the blotter-roller 21.

The operation of a preferred embodiment of the present inventive systemis illustrated in FIG. 4 wherein applicator-blotter roller 14substantially simultaneously applies the required solvent or heat tomigration imaging member 10, as the same roller 14 also blots up theresidue comprising unmigrated photosensitive material, undissolvedparticles of softenable layer 11, and excess solvent. It is understoodthat the dual roller system 19 of FIG. 3 may similarly be used in conjunction with the migration imaging member 10 in another preferredembodiment of the present inventive system. Likewise, any suitable meansmay be used in place of applicator roller 20, so that the medium beingused to soften the softenable layer can be suitably applied.

The novel structure for a migration imaging member preferred for use inthe present inventive system is illustrated in FIG. 5, wherein substrate23 supports softenable layer 24. In FIG. 5(a) the softenable layer 24 iscoated with a fracturable layer of migration marking material 25, andadvantageous layer 26 is an electrically insulating, porous, absorbentlayer which overlies the fracturable layer 25. In FIG. 5(b) migrationmarking particles 25 are dispersed throughout the softenable layer 24 ina matrix configuration. In preferred embodiments of the novel imagingmember, the migration marking material or particles are electricallyphotosensitive. Any one of these embodiments is suitable for use withthe advantageous migration imaging member development system of thepresent invention.

The electrically photosensitive material or particles, portions of whichmigrate to the substrate during image formation, may comprise anysuitable electrically photosensitive material which is typically notreadily soluble in any of the media used to soften the softenable layerduring development of the migration imaging member. Preferably,photosensitive materials in particle form should be about 0.0l to about3 microns in size and optimally about 0.5 to about I microns in size foroptimum resolution and otherwise high quality images according to thisinvention.

Electrically photosensitive particles as used herein refers to anyparticles which when dispersed in a softenable, electrically insulatingbinder or matrix layer as described herein, in response to electricalcharging, imagewise exposure to activating radiation, and contact withsuitable softening media, are caused to selectively deposit in imageconfiguration on a substrate.

While photoconductive particles, (and photoconductive" is used in itsbroadest sense to mean particles which show increased electricalconductivity when illuminated with electromagnetic radiation and notnecessarily only those which have been found to be useful in xerographyin xerographic pigment-binder plate configurations) have been found tobe a class of particles useful as electrically photosensitive particlesin this invention and while the photoconductive effect is oftensufficient in the present invention to provide in electricallyphotosensitive material, photoconductivity does not appear to be anecessary effect. Apparently the necessary effect according to theinvention is the selective relocation of charge into, within or out ofthe material or particles, said relocation being effected by lightacting on the bulk or surface of the electrically photosensitivematerial, by exposing said material or particle to activating radiationwhich may specifically include photoconductive effects, photoinjection,photoemission, photochemical effects and others which cause saidselective relocation of charge.

The absorbent layer 26 is itself preferably substantially electricallyinsulating so that electrostatic latent images or charge patterns on theimaging member, and particularly on the photosensitive layer of suchlayered embodiments of the imaging member, will not be dissipatedthrough the absorbent overlayer.

The substrate, and therefore also the other layers of the migrationimaging member typically adhered to said substrate, may generally be inany suitable form such as a strip, sheet, plate, coil, cylinder, drum,endless belt, moebius strip, circular disk or the like, depending uponthe specific embodiment of the novel migration imaging system. Thesubstrate may be electrically conductive or insulating. Conductivesubstrates generally facilitate the charging or sensitization of theimaging member according to the optimum electricaloptical mode of theinvention. However, electrically insulating substrates open up a widevariety of film formable synthetic materials for use as the substrate.

The softenable layer may be coated directly into the conductivesubstrate, or alternatively, the softenable layer may be self-supportingand may be brought into contact with a suitable substrate duringimaging. The softenable layer may comprise one or more layers ofsoftenable materials. The softenable layer should preferably besubstantially electrically insulating for use in the optimumeIectricaLoptical mode, especially during the migration force applyingand softening steps; but, more conductive materials may be used in otherelectrical modes of the imaging system wherein a constant andreplenishing supply of charges in image configuration is applied to theimaging member. The softenable layer may be one or more layers of anysuitable thickness, with thicker layers generally requiring a greaterelectrostatic potential in various modes of the migration imagingsystem. Thicknesses in the range of about A to about 16 microns havebeen found preferable for use in such imaging systems.

Materials suitable for use as substrates, softenable layers, andmigration marking particles in such a migration imaging system, are morefully discussed in copending applications Ser. No. 837,780, filed June30, 1969, and Ser. No. 837,591, filed June 30, 1969.

The substantially electrically insulating, porous and absorbent member,layer, membrane, sheet or web 26, in FIG. 5, generally sufficientlyporous to allow passage of solvent fluid, either liquid or vapor, andyet substantially insoluble in the particular solvent used. This layeris also sufficiently absorbent or adhesive to substantially completelyabsorb, blot, or pick up residual unmigrated particles, undissolvedparticles of the softenable layer, and excess solvent, from the desiredimaged member comprising the substrate supporting the migratedphotosensitive particles. The absorbent sheet is also preferablysubstantially electrically insulating so that in the layeredconfigurations such as shown in FIG. 5(a), the charge image pattern onthe fracturable layer is not dissipated by contact with the absorbentlayer. For example, absorbent, substantially insulating layers havingbulk resistivities greater than about 10 ohm-centimeters an preferredfor use in the present invention. Absorbent layers of thicknesses lessthan about 200 microns are similarly preferred.

This layer is typically a porous membrane, sheet, or web, selected toadequately perform with the solvent, migration particles, and softenablelayer, comprising the particular migration imaging system. Examples ofmaterials typically used for the insulating absorbent layer includeXerox 914 Bond available from Xerox Corporation, Rochester, N.Y.; A-IMMimeograph Master stencil tissue, available from Addressograph-Multigraph Corporation; Brown (Companys carbonizing tissue; Delseytoilet tissue; Bible tissue, available from Weyerhausen Papers; OlinPapers unbleached tissue paper. A particularly preferred material isOlin Papers unbleached 10 lb. single-side glazed tissue typi cally madeas a carbon paper base.

It will also be appreciated that when the heat softening system ratherthan a solvent softening system is used with a migration imaging member,that the absorbent layer need not be porous if it is otherwise asuitable conductor of heat and is not itself susceptible to being meltedby the heat necessary to soften the softenable layer in the migrationimaging member. Again, however, the layer used with the heat softeningsystem must have the requisite absorptive or adhesive characteristics.

Another preferred embodiment of the present inventive system isillustrated in FIG. 6 wherein the novel migrationimaging memberillustrated in FIG. 5 is cooperatively used in conjunction with asuitable roller applicator 27 which is shown applying solvent throughporous layer 26 at point 28, after which porous, blotting layer 26 isremoved from the remainder of the novel migration imaging structure,with layer 26 having absorbed and absorbed residual photosensitiveparticles, parts of the softenable layer, and excess solvent, shown at29. Substrate 23 supports migrated image 30 comprising photosensitiveparticles which migrated to substrate 23 after the imaging member wascharged, exposed and the developing solvent or heat applied by theadvantageous system of the present invention.

In FIG. 7, the novel migration imaging system is illustrated in anotherpreferred embodiment wherein the novel migration imaging memberillustrated in FIG. 5 is cooperatively used in conjunction with sprayapplicator 31 which applies liquid or vapor solvent to the migrationimaging member through insulating, porous layer 26 in the area indicatedat 32. Thereafter, porous blotting layer 26 is removed from theremaining substrate 23 supporting the migrated photosensitive particlescomprising the developed image 33, and said porous blotting layer 26 hasabsorbed residual photosensitive particles, parts of the softenablelayer, and excess solvent, shown adhering to it at 34.

In FIG. 8, the novel migration imaging system just described and asillustrated in FIG. 6, is shown in cooperation with means 35 forexposing a photosensitive migration imaging member to a light-and-shadowimage pattern 36, said exposure taking place from the side ofsubstantially transparent substrate 23 opposite the side supporting theremaining layers 24, 25, 26 of the novel migration imaging member of thepresent invention. Similarly, FIG. 9 illustrates a novel migrationimaging member being used in cooperation with means 35 for exposing thephotosensitive imaging member to a lightand-shadow image pattern fromthe side of substantially transparent absorbent blotter layer 26. Forexample a bleached tissue layer 26 saturated with solvent during theexposure step may be used in this embodiment. Also, substantially heatfusible low melting waxes may also perform this function. It will beunderstood that any means suitable for exposing the inventive imagingmember to a light-and-shadow image may be used as shown in FIGS. 8 and9. It will also be appreciated that the system shown in FIG. 9 requiresthat the absorbent layer 26 be substantially transparent to allowpassage of sufiicient light to effect the photosensitive particles sothat an image of the desired quality is formed. When such an absorbentlayer 26 is not used, an appropriately transparent substrate must beused so that the system illustrated in FIG. 8 may be used.

The advantageous imaging system of the present invention may also beused with migration imaging members whose fracturable layers or binderstructures utilize marking material comprising non-photosensitive orphotosensitively inert materials. In such systems, as described forexample in copending application Ser. No. 483,675, filed Aug. 30, 1965,now U.S. Pat. No. 3,656,990, the latent image may be formed by any of awide variety of methods including charging in image configurationthrough the use of a mask or stencil; first forming such a chargepattern on a separate photoconductive insulating layer according toconventional xerographic reproduction techniques and then transferringthis charge pattern to the imaging member by bringing the two layersinto very close proximity and utilizing breakdown techniques asdescribed, for example, in Carlson U.S. Pat. No. 2,982,647 and WalkupU.S. Pat. Nos. 2,825,814 and 2,937,943. In addition, charge patternsconforming to selected, shaped, electrodes or combinations of electrodesmay be formed by the TESI discharge technique as more fully described inSchwertz U.S. Pat. Nos. 3,023,731 and 2,919,967 or by techniquesdescribed in Walkup U.S. Pat. Nos. 3,001,848 and 3,001,849 as well as byelectron Walkup U.S. Pat. Nos. 3,001,848 and 3,001,849 as well as byelectron beam recording techniques, for example as described in GlennU.S. Pat. No. 3,113,179.

It will be appreciated that migration imaging systems involving thenovel migration imaging member of this invention, provide a systemwherein the development oflatent images upon said imaging member may becarried out in a simpler, neater, and more expedient manner, than inprevious embodiments of solvent washaway, solvent vapor softening, orheat softening development. The absorbent layer used in the presentinvention may be a permanent recyclable web, or it may be a disposablelayer which is discarded after performing its function during a singleimaging of such a migration imaging member. As such, the system of thepresent invention is quite practical for adaptation to automatic imagingapparatus.

The following examples further specifically define the present inventionwith respect to a novel migration imaging system. The parts andpercentages are by weight unless otherwise indicated. The examples beloware intended to illustrate various preferred embodiments of the novelmigration imaging member and development system.

EXAMPLE I The novel system for development of migration imaging memberis performed using a migration imaging member comprising an about S-milaluminum substrate coated with a layer of a matrix of softenablematerial containing photosensitive particles. The matrix mixture iscomposed of about a 3:1 ratio of a petroleum hydrocarbon resin with acolor of G-l 0 on the Gardner scale, Piccopale -SF, available fromPennsylvania Industrial Chemical Co., to x-form metal-freephthalocyanine as described in Byrne U.S. Pat. No. 3,357,989. The 3:1ratio of resin and phthalocyanine particles is ground in a long-chainsaturated aliphatic hydrocarbon liquid, boiling point 315350F., Isopar Gsolvent, available from Humble Oil Co. and coated on the aluminumsubstrate with an about 0.0005 inch Bird applicator bar available fromGardner Laboratories. The coated aluminum substrate is then dried forabout 10 minutes at about C. This method of application substantiallyuniformly disperses the photosensitive phthalocyanine particlesthroughout the resin matrix. This photosensitive migration imagingmember is then negatively charged by a corona charging device and thecharged member is exposed to the desired tungsten filamentlight-and-shadow image pattern by projection of said pattern upon theimaging member using an exposure of about 50 f.c.s. The latent imagedmember is then covered with an overlayer of substantially insulatingabsorbent, blotting material, in this case A-M Master Stencal Tissue,available from Addressograph- Multigraph Corporation. Xylene solvent isapplied by means of a roller hving a microporous polyurethane foam resinsponge absorptive surface. After the application of the xylene solvent,the blotting material sheet having absorbed residual unmigratedphotosensitive particles, undissolved particles of the softenable layer,and excess solvent, is removed from the imaging member. The remainingportion of the imaged member is the substrate supporting the migratedphotosensitive particles in the desired image configuration.

This system yields, on the substrate, sharp positive images of excellentdensity and very low background. On the blotting material sheet removedfrom said imaging member, lateral diffusion of the photosensitivemarking particles between the tissue fibers blurs the negative patternpicked up by the blotting sheet, therefore rendering the latter patterncommercially unacceptable.

EXAMPLE II A migration imaging member suitable for use in the inventivesystem is constructed by coating an insulating about 3-mil Mylarpolyester film, available from E. I.

duPont deNemours & Co., Inc., with a softenable material, StabeliteEster 10, available from Hercules Powder Company. A fracturablemigration layer of selenium is vacuum evaporated onto the Stabelitesoftenable layer by exposing the softenable layer to selenium vapors ata vacuum of about 4 X Torr for about 2 seconds. This imaging member isimaged by charging and exposing as described in Example I. The image isdeveloped by the application of Sohio 3440 hydrocarbon solvent,available from the Standard Oil Company of Ohio. The developing solventis applied by a roller having a microporous, absorbent surface ofpolyurethane sponge material. As the polyurethane roller applies thesolvent, it substantially simultaneously picks up and absorbs unmigratedselenium marking material and residual solvent and dissolved Stabelitefrom the softenable layer. The developed image member remains having theimagewise marking particles in image configuration on the Mylarsubstrate.

EXAMPLE Ill The novel system for development of migration imagingmembers is performed using a novel migration imaging member comprising asubstrate of about 3 mils in thickness composed of polyethyleneterephthalate, called Mylar" and available from E. I. duPont deNemours &Co., overcoated with a thin layer of aluminum which is about 50 percentwhite light transmissive. The aluminizedMylar substrate is coated with aphotoconductive matrix as described in Example I, in addition anoverlayer of substantially electrically insulating absorbent blottingmaterial, in this case a sheet of 10 lb. 17 in. X 22 in., 500 sheetream) glazed carbonizing tissue manufactured by Olin Industries. Theimaging member is then negatively charged with a corona charging deviceand is exposed as described in Example I. However, the exposure step inthis embodiment is performed through the substantially transparentaluminized Mylar substrate. The xylene solvent is then applied by meansof a spray head which produces an effective spray width equal to thewidth of the migration imaging member. The spray head applies thesolvent onto and through the blotting tissue layer which absorbsresidual unmigrated photosensitive particles, undissolved particles ofthe softenable layer, and excess solvent. The blotting tissue, thensaturated with the residual products of solvent development of themigration imaging member, is removed from said imaging member. Thesubstrate remains supporting the migrated photosensitive particles inimage configuration. This system also yields sharp positive images ofgood density and low background.

Although specific components, proportions and procedures have beenstated in the above description of the preferred embodiments of thenovel migration imaging system, other suitable materials, as listedabove, may be used with similar results. In addition, it may be thatother substances exist or may be discovered that have some or enough ofthe properties of the particular substances described herein to be usedas substitutes, or that other materials and procedures may be employedto synergize, enhance or otherwise modify the novel migration imagingsystem.

Such other modifications and ramifications of the present invention willoccur to those skilled in the art upon a reading of this disclosure.These are intended to be included within the scope of this invention.

What is claimed is: l. A migration imaging method comprising: providingan imaging member comprising a substrate, a layer of substantiallyelectrically insulating softenable material overlying said substrate,said softenable material containing migration marking material, saidsoftenable material capable of having its resistance to migration ofmigration marking material decreased sufficiently to allow migration ofmigration marking material in depth in said softenable material, and asubstantially electrically insulating absorbent blotter layer capable ofabsorbing migration marking material and softenable material overlyingthe surface of the layer of softenable material; I providing anelectrical latent image on said member; developing said imaging memberby decreasing the resistance to migration of migration marking materialin depth in the layer of softenable material at least sufficient toallow imagewise migration of migration marking material at least indepth in said softenable layer; applying a solvent for said softenablematerial to said absorbent blotter layer whereby said softenablematerial and migration marking material are capable of being absorbed inan absorbent blotter layer;

and removing the absorbent blotter layer, which contains the liquidsolvent for the softenable material, thereby removing residual migrationmarking material and residual softenable material which are absorbed bythe absorbent blotter layer when contacted, leaving an imaged substratecomprising migration marking material in imagewise configuration on saidsubstrate.

2. The method of claim 1 wherein said substrate is electricallyconductive.

3. The method of claim 1 wherein said substrate is substantiallyelectrically insulating.

4. The method of claim 1 wherein said substrate is sufficientlytransparent to transmit a visible image.

5. The method of claim 1 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about 1% and about 16 microns.

6. The method of claim 1 wherein said migration marking material isparticulate material of average particle size in the range between about0.01 and about 3 microns.

7. The method of claim 6 wherein said migration marking material isparticulate material of average par ticle size in the range betweenabout 0.5 and about 1 micron. t v

8. The method of claim 1 wherein said migration marking materialcomprises electrically photosensitive material.

9. The method of claim 8 wherein said substrate is sufficientlytransparent to transmit activating electromagnetic radiation which iscapable of affecting said electrically photosensitive material.

10. The method of claim 8 wherein said substantially electricallyinsulating absorbent blotter layer is sufficiently transparent totransmit activating electromagnetic radiation which is capable ofaffecting said electrically photosensitive material.

11. The method of claim 1 wherein said electrical latent image comprisesan electrostatic latent image.

12. The method of claim 1 wherein a latently imaged member is developedby applying a solvent liquid to said member, wherein said solvent liquidis a solvent for said softenable material and wherein said solventliquid does not substantially degrade the migration marking material,the substrate, and the absorbent blotter layer.

13. The method of claim 12 wherein said liquid solvent is rolled ontoand through said absorbent blotter layer.

14. The method of claim 12 wherein said liquid solvent is sprayed ontoand through said absorbent blotter layer.

15. The method of claim 1 wherein the latently imaged member isdeveloped by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

16. The method of claim 1 wherein the latently imaged member isdeveloped by heating the softenable material in an amount sufficient todecrease the resistance of the softenable material to migration of themigration marking material.

17. The method of claim 1 wherein said substantially electricallyinsulating absorbent blotter layer comprises the surface of an absorbentroller.

18. The method of claim 17 wherein said surface of said absorbent rollercontains a liquid or vaporous solvent for the softenable material andsaid roller is rolled across the surface of the layer of softenablematerial, thereby simultaneously developing the latently imaged memberand removing residual migration marking material and residual softenablematerial.

19. The method of claim 1 wherein said migration marking material isarranged in a fracturable layer of said material contiguous the surfaceof said softenable layer over which the absorbent blotter layer lies,and said fracturable layer of migration marking material is spaced apartfrom the surface of the softenable layer which overlies the substrate.

20. The method of claim 19 wherein the migration imaging memberadditionally comprises a second layer of substantially electricallyinsulating softenable material overlying the fracturable layer ofmigration marking material and located between said fracturable layerand the absorbent blotter layer.

21. The method of claim 19 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about 6 and about 16 microns.

22. The method of claim 19 wherein said migration marking material isparticulate material of average particle size in the range between about0.01 and about 3 microns.

23. The method of claim 19 wherein said migration marking materialcomprises electrically photosensitive material.

24. The method of claim 23 wherein said substrate is sufficientlytransparent to transmit activating electromagnetic radiation which iscapable of affecting said electrically photosensitive material.

25. The method of claim 23 wherein said substantially electricallyinsulating absorbent blotter layer is sufficiently transparent totransmit activating electromagnetic radiation which is capable ofaffecting said electrically photosensitive material.

26. The method of claim 19 wherein said electrical latent imagecomprises an electrostatic latent image.

27. The method of claim 19 wherein a latently imaged member is developedby applying a solvent liquid to said member, wherein said solvent liquidis a solvent for said softenable material and wherein said solventliquid does not substantially degrade the migration marking material,the substrate, and the absorbent blotter layer.

28. The method of claim 19 wherein the latently imaged member isdeveloped by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

29. The method of claim 19 wherein the latently imaged member isdeveloped by heating the softenable material in an amount sufficient todecrease the resistance of the softenable material to migration of themigration marking material.

30. The method of claim 1 wherein said migration marking material isdispersed throughout the layer of softenable material.

31. The method of claim 30 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about and about 16 microns.

32. The method of claim 30 wherein said migration marking material isparticulate material of average particle size in the range between about0.0l and about 3 microns.

33. The method of claim 30 wherein said'migration marking materialcomprises electrically photosensitive material.

34. The method of claim 33 wherein said substrate is sufficientlytransparent to transmit activating electromagnetic radiation which iscapable of affecting said electrically photosensitive material.

35. The method of claim 33 wherein said substantially electricallyinsulating absorbent blotter layer is sufficiently transparent totransmit activating electromagnetic radiation which is capable ofeffecting said electrically photosensitive material.

36. The method of claim 30 wherein said electrical latent imagecomprises an electrostatic latent image.

37. The method of claim 30 wherein a latently imaged member is developedby applying a solvent liquid to said member, wherein said solvent liquidis a solvent for said softenable material and wherein said solventliquid does not substantially degrade the migration marking material,the substrate, and the absorbent blotter layer.

38. The method of claim 30 wherein the latently imaged member isdeveloped by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

39. The method of claim 30 wherein the latently imaged member isdeveloped by heating the softenable material in an amount sufficient todecrease the resistance of the softenable material to migration of themigration marking material.

40. The method of claim 30 wherein said imaging member is provided byplacing a substantially electrically insulating absorbent blotter layeron the surface of a layer of substantially electrically insulatingsoften able material which contains migration marking material and whichoverlies a substrate.

41. The method of claim 40 wherein said substantially electricallyinsulating absorbent blotter layer comprises the surface of an absorbentroller.

42. A migration imaging method comprising:

providing an imaging member comprising a substrate, a layer ofsubstantially electrically insulating softenable material overlying saidsubstrate, said softenable material containing migration markingmaterial, said softenable material capable of having its resistance tomigration of migration marking material decreased sufficiently to allowmigration of migration marking material in depth in said softenablematerial;

providing an electrical latent image on said member;

developing said imaging member by decreasing the resistance to migrationof migration marking material in depth in the layer of softenablematerial at least sufficient to allow imagewise migration of migrationmaterial at least in depth in said softenable layer;

applying a solvent for said softenable material whereby said softenablematerial and said migration marking material are capable of beingabsorbed in the absorbent blotter layer recited below; contacting saidimaged member with a substantially electrically insulating absorbentblotter layer capable of absorbing migration marking material andsoftenable material;

and removing the absorbent blotter layer thereby removing residualmigration marking material and residual softenable material which arecontacted by the absorbent blotter layer, leaving an imaged substratecomprising migration marking material in imagewise configuration on saidsubstrate.

43. The method according to claim 42 wherein said substrate iselectrically conductive.

44. The method according to claim 42 wherein said substrate issubstantially electrically insulating.

45. The method according to claim 42 wherein said substrate issufficiently transparent to transmit a visible image.

46. The method according to claim 42 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about A and about 16 microns.

47. The method according to claim 42 wherein said migration markingmaterial is particulate material of average particle size in the rangebetween about 0.01 and about 3 microns.

48. The method according to claim 47 wherein said migration markingmaterial is particulate material of average particle size in the rangebetween about 0.5 and about 1 micron.

49. The method according to claim 42 wherein said migration markingmaterial comprises electrically photosensitive material.

50. The method according to claim 49 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.

51. The method according to claim 42 wherein said electrical latentimage comprises an electrostatic latent Image.

52. The method according to claim 42 wherein a latently imaged member isdeveloped by applying a solvent liquid to said member, wherein saidsolvent liquid is a solvent for said softenable material and whereinsaid solvent liquid does not substantially degrade the migration markingmaterial, the substrate, and the absorbent blotter layer.

53. The method according to claim 42 wherein the latently imaged memberis developed by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

54. The method according to claim 42 wherein the latently imaged memberis developed by heating the softenable material.

55. The method according to claim 42 wherein said substantiallyelectrically insulating absorbent blotter layer comprises the surface ofan absorbent roller.

56. The method according to claim 55 wherein said surface of saidabsorbent roller contains a liquid or vaporous sol-vent for thesoftenable material and said roller is rolled across the surface of thelayer of softenable material, thereby simultaneously developing thelatently imaged member and removing residual migration marking materialand residual softenable material.

57. The method according to claim 42 wherein said migration markingmaterial is arranged in a fracturable layer of said material contiguousthe surface of said softenable layer and said fracturable layer ofmigration marking materialis spaced apart from the surface of thesoftenable layer which overlies the substrate.

58. The method according to claim 57 whereinsaid layer of substantiallyelectrically insulating softenable material is of a thickness of therange between about 1/2 and about 16 microns.

59. The method according to claim 57 wherein said migration markingmaterial is particulate material of average particle size in the rangebetween about 0.01 and about 3 microns. I

60. The method according to claim 57 wherein said migration markingmaterial comprises electrically photosensitive material.

61. The methodaccording to claim 60 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.

62. The method according to claim 57 wherein said electrical latentimage comprises an electrostatic latent image.

63. The method according to claim 57 wherein a la tently imaged memberis developed by applying a solvent liquid to said member, wherein saidsolvent liquid is a solvent for said softenable material and whereinsaid solvent liquid does not substantially degrade the migration markingmaterial, the substrate, and the absorbent blotter layer.

64. The method according to claim 57 wherein the latently imaged memberis developed by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

65. The method according to claim 57 wherein the latently imaged memberis developed by heating the softenable material.

66. The method according to claim 19 wherein said substantiallyelectrically insulating absorbent blotter layer comprises the surface ofan absorbent roller.

67. The method according to claim 66 wherein said surface of saidabsorbent roller contains a liquid or vaporous solvent for thesoftenable material and said roller is rolled across the surface of thelayer of softenable material, thereby simultaneously developing thelatently imaged member and removing residual migration marking materialand residual softenable material.

68. The method according to claim 42 wherein said migration markingmaterial is dispersed throughout the layer of softenable material.

69. The method according to claim 68 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about 9% and about 16 microns.

70. The method according to claim 68 wherein said migration markingmaterial is particulate material of average particle size in the rangebetween about 0.01 and about 3 microns.

71. The method according to claim 68 wherein said migration markingmaterial comprises electrically photosensitive material.

72. The method according to claim 71 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.

73. The method according to claim 68 wherein said electrical latentimage comprises an electrostatic latent image.

74. The method according to claim 68 wherein a latently imaged member isdeveloped by applying a solvent liquid to said member, wherein saidsolvent liquid is a solvent for said softenable material and whereinsaid solvent liquid does not substantially degrade the migration markingmaterial, the substrate, and the absorbent blotter layer.

75. The method according to claim 68 wherein the latently imaged memberis developed by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer.

76. The method according to claim 68 wherein the latently imaged memberis developed by heating the softenable material.

77. The method according to claim 68 wherein said substantiallyelectrically insulating absorbent blotter layer comprises the surface ofan absorbent roller.

78. The method according to claim 77 wherein said surface of saidabsorbent roller contains a liquid or vaporous solvent for thesoftenable material and said roller is rolled across the surface of thelayer of softenable material, thereby simultaneously developing thelatently imaged member and removing residual migration marking materialand residual softenable material. k

2. The method of claim 1 wherein said substrate is electricallyconductive.
 3. The method of claim 1 wherein said substrate issubstantially electrically insulating.
 4. The method of claim 1 whereinsaid substrate is sufficiently transparent to transmit a visible image.5. The method of claim 1 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about 1/2 and about 16 microns.
 6. The method of claim 1wherein said migration marking material is particulate material ofaverage particle size in the range between about 0.01 and about 3microns.
 7. The method of claim 6 wherein said migration markingmaterial is particulate material of average particle size in the rangebetween about 0.5 and about 1 micron.
 8. The method of claim 1 whereinsaid migration marking material comprises electrically photosensitivematerial.
 9. The method of claim 8 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.
 10. The method of claim 8 wherein said substantiallyelectrically insulating absorbent blotter layer is sufficientlytransparent to transmit activating electromagnetic radiation which iscapable of affecting said electrically photosensitive material.
 11. Themethod of claim 1 wherein said electrical latent image comprises anelectrostatic latent image.
 12. The method of claim 1 wherein a latentlyimaged member is developed by applying a solvent liquid to said member,wherein said solvent lIquid is a solvent for said softenable materialand wherein said solvent liquid does not substantially degrade themigration marking material, the substrate, and the absorbent blotterlayer.
 13. The method of claim 12 wherein said liquid solvent is rolledonto and through said absorbent blotter layer.
 14. The method of claim12 wherein said liquid solvent is sprayed onto and through saidabsorbent blotter layer.
 15. The method of claim 1 wherein the latentlyimaged member is developed by applying a solvent vapor to said member,wherein said solvent vapor is a solvent vapor for the softenablematerial, and wherein said solvent vapor does not substantially degradethe migration marking material, the substrate, and the absorbent blotterlayer.
 16. The method of claim 1 wherein the latently imaged member isdeveloped by heating the softenable material in an amount sufficient todecrease the resistance of the softenable material to migration of themigration marking material.
 17. The method of claim 1 wherein saidsubstantially electrically insulating absorbent blotter layer comprisesthe surface of an absorbent roller.
 18. The method of claim 17 whereinsaid surface of said absorbent roller contains a liquid or vaporoussolvent for the softenable material and said roller is rolled across thesurface of the layer of softenable material, thereby simultaneouslydeveloping the latently imaged member and removing residual migrationmarking material and residual softenable material.
 19. The method ofclaim 1 wherein said migration marking material is arranged in afracturable layer of said material contiguous the surface of saidsoftenable layer over which the absorbent blotter layer lies, and saidfracturable layer of migration marking material is spaced apart from thesurface of the softenable layer which overlies the substrate.
 20. Themethod of claim 19 wherein the migration imaging member additionallycomprises a second layer of substantially electrically insulatingsoftenable material overlying the fracturable layer of migration markingmaterial and located between said fracturable layer and the absorbentblotter layer.
 21. The method of claim 19 wherein said layer ofsubstantially electrically insulating softenable material is of athickness in the range between about 1/2 and about 16 microns.
 22. Themethod of claim 19 wherein said migration marking material isparticulate material of average particle size in the range between about0.01 and about 3 microns.
 23. The method of claim 19 wherein saidmigration marking material comprises electrically photosensitivematerial.
 24. The method of claim 23 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.
 25. The method of claim 23 wherein said substantiallyelectrically insulating absorbent blotter layer is sufficientlytransparent to transmit activating electromagnetic radiation which iscapable of affecting said electrically photosensitive material.
 26. Themethod of claim 19 wherein said electrical latent image comprises anelectrostatic latent image.
 27. The method of claim 19 wherein alatently imaged member is developed by applying a solvent liquid to saidmember, wherein said solvent liquid is a solvent for said softenablematerial and wherein said solvent liquid does not substantially degradethe migration marking material, the substrate, and the absorbent blotterlayer.
 28. The method of claim 19 wherein the latently imaged member isdeveloped by applying a solvent vapor to said member, wherein saidsolvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer. 29.The method of claim 19 wherein the latently imaged member is developedby heating the softenable material in an amount sufficIent to decreasethe resistance of the softenable material to migration of the migrationmarking material.
 30. The method of claim 1 wherein said migrationmarking material is dispersed throughout the layer of softenablematerial.
 31. The method of claim 30 wherein said layer of substantiallyelectrically insulating softenable material is of a thickness in therange between about 1/2 and about 16 microns.
 32. The method of claim 30wherein said migration marking material is particulate material ofaverage particle size in the range between about 0.01 and about 3microns.
 33. The method of claim 30 wherein said migration markingmaterial comprises electrically photosensitive material.
 34. The methodof claim 33 wherein said substrate is sufficiently transparent totransmit activating electromagnetic radiation which is capable ofaffecting said electrically photosensitive material.
 35. The method ofclaim 33 wherein said substantially electrically insulating absorbentblotter layer is sufficiently transparent to transmit activatingelectromagnetic radiation which is capable of effecting saidelectrically photosensitive material.
 36. The method of claim 30 whereinsaid electrical latent image comprises an electrostatic latent image.37. The method of claim 30 wherein a latently imaged member is developedby applying a solvent liquid to said member, wherein said solvent liquidis a solvent for said softenable material and wherein said solventliquid does not substantially degrade the migration marking material,the substrate, and the absorbent blotter layer.
 38. The method of claim30 wherein the latently imaged member is developed by applying a solventvapor to said member, wherein said solvent vapor is a solvent vapor forthe softenable material, and wherein said solvent vapor does notsubstantially degrade the migration marking material, the substrate, andthe absorbent blotter layer.
 39. The method of claim 30 wherein thelatently imaged member is developed by heating the softenable materialin an amount sufficient to decrease the resistance of the softenablematerial to migration of the migration marking material.
 40. The methodof claim 30 wherein said imaging member is provided by placing asubstantially electrically insulating absorbent blotter layer on thesurface of a layer of substantially electrically insulating softenablematerial which contains migration marking material and which overlies asubstrate.
 41. The method of claim 40 wherein said substantiallyelectrically insulating absorbent blotter layer comprises the surface ofan absorbent roller.
 42. A migration imaging method comprising:providing an imaging member comprising a substrate, a layer ofsubstantially electrically insulating softenable material overlying saidsubstrate, said softenable material containing migration markingmaterial, said softenable material capable of having its resistance tomigration of migration marking material decreased sufficiently to allowmigration of migration marking material in depth in said softenablematerial; providing an electrical latent image on said member;developing said imaging member by decreasing the resistance to migrationof migration marking material in depth in the layer of softenablematerial at least sufficient to allow imagewise migration of migrationmaterial at least in depth in said softenable layer; applying a solventfor said softenable material whereby said softenable material and saidmigration marking material are capable of being absorbed in theabsorbent blotter layer recited below; contacting said imaged memberwith a substantially electrically insulating absorbent blotter layercapable of absorbing migration marking material and softenable material;and removing the absorbent blotter layer thereby removing residualmigration marking material and residual softenable material which arecontacted by the absorbent blotter layer, leaving an imaged subsTratecomprising migration marking material in imagewise configuration on saidsubstrate.
 43. The method according to claim 42 wherein said substrateis electrically conductive.
 44. The method according to claim 42 whereinsaid substrate is substantially electrically insulating.
 45. The methodaccording to claim 42 wherein said substrate is sufficiently transparentto transmit a visible image.
 46. The method according to claim 42wherein said layer of substantially electrically insulating softenablematerial is of a thickness in the range between about 1/2 and about 16microns.
 47. The method according to claim 42 wherein said migrationmarking material is particulate material of average particle size in therange between about 0.01 and about 3 microns.
 48. The method accordingto claim 47 wherein said migration marking material is particulatematerial of average particle size in the range between about 0.5 andabout 1 micron.
 49. The method according to claim 42 wherein saidmigration marking material comprises electrically photosensitivematerial.
 50. The method according to claim 49 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.
 51. The method according to claim 42 wherein said electricallatent image comprises an electrostatic latent image.
 52. The methodaccording to claim 42 wherein a latently imaged member is developed byapplying a solvent liquid to said member, wherein said solvent liquid isa solvent for said softenable material and wherein said solvent liquiddoes not substantially degrade the migration marking material, thesubstrate, and the absorbent blotter layer.
 53. The method according toclaim 42 wherein the latently imaged member is developed by applying asolvent vapor to said member, wherein said solvent vapor is a solventvapor for the softenable material, and wherein said solvent vapor doesnot substantially degrade the migration marking material, the substrate,and the absorbent blotter layer.
 54. The method according to claim 42wherein the latently imaged member is developed by heating thesoftenable material.
 55. The method according to claim 42 wherein saidsubstantially electrically insulating absorbent blotter layer comprisesthe surface of an absorbent roller.
 56. The method according to claim 55wherein said surface of said absorbent roller contains a liquid orvaporous sol-vent for the softenable material and said roller is rolledacross the surface of the layer of softenable material, therebysimultaneously developing the latently imaged member and removingresidual migration marking material and residual softenable material.57. The method according to claim 42 wherein said migration markingmaterial is arranged in a fracturable layer of said material contiguousthe surface of said softenable layer and said fracturable layer ofmigration marking material is spaced apart from the surface of thesoftenable layer which overlies the substrate.
 58. The method accordingto claim 57 wherein said layer of substantially electrically insulatingsoftenable material is of a thickness of the range between about 1/2 andabout 16 microns.
 59. The method according to claim 57 wherein saidmigration marking material is particulate material of average particlesize in the range between about 0.01 and about 3 microns.
 60. The methodaccording to claim 57 wherein said migration marking material compriseselectrically photosensitive material.
 61. The method according to claim60 wherein said substrate is sufficiently transparent to transmitactivating electromagnetic radiation which is capable of affecting saidelectrically photosensitive material.
 62. The method according to claim57 wherein said electrical latent image comprises an electrostaticlatent image.
 63. The method according to claim 57 wherein a latentlyimageD member is developed by applying a solvent liquid to said member,wherein said solvent liquid is a solvent for said softenable materialand wherein said solvent liquid does not substantially degrade themigration marking material, the substrate, and the absorbent blotterlayer.
 64. The method according to claim 57 wherein the latently imagedmember is developed by applying a solvent vapor to said member, whereinsaid solvent vapor is a solvent vapor for the softenable material, andwherein said solvent vapor does not substantially degrade the migrationmarking material, the substrate, and the absorbent blotter layer. 65.The method according to claim 57 wherein the latently imaged member isdeveloped by heating the softenable material.
 66. The method accordingto claim 19 wherein said substantially electrically insulating absorbentblotter layer comprises the surface of an absorbent roller.
 67. Themethod according to claim 66 wherein said surface of said absorbentroller contains a liquid or vaporous solvent for the softenable materialand said roller is rolled across the surface of the layer of softenablematerial, thereby simultaneously developing the latently imaged memberand removing residual migration marking material and residual softenablematerial.
 68. The method according to claim 42 wherein said migrationmarking material is dispersed throughout the layer of softenablematerial.
 69. The method according to claim 68 wherein said layer ofsubstantially electrically insulating softenable material is of athickness in the range between about 1/2 and about 16 microns.
 70. Themethod according to claim 68 wherein said migration marking material isparticulate material of average particle size in the range between about0.01 and about 3 microns.
 71. The method according to claim 68 whereinsaid migration marking material comprises electrically photosensitivematerial.
 72. The method according to claim 71 wherein said substrate issufficiently transparent to transmit activating electromagneticradiation which is capable of affecting said electrically photosensitivematerial.
 73. The method according to claim 68 wherein said electricallatent image comprises an electrostatic latent image.
 74. The methodaccording to claim 68 wherein a latently imaged member is developed byapplying a solvent liquid to said member, wherein said solvent liquid isa solvent for said softenable material and wherein said solvent liquiddoes not substantially degrade the migration marking material, thesubstrate, and the absorbent blotter layer.
 75. The method according toclaim 68 wherein the latently imaged member is developed by applying asolvent vapor to said member, wherein said solvent vapor is a solventvapor for the softenable material, and wherein said solvent vapor doesnot substantially degrade the migration marking material, the substrate,and the absorbent blotter layer.
 76. The method according to claim 68wherein the latently imaged member is developed by heating thesoftenable material.
 77. The method according to claim 68 wherein saidsubstantially electrically insulating absorbent blotter layer comprisesthe surface of an absorbent roller.
 78. The method according to claim 77wherein said surface of said absorbent roller contains a liquid orvaporous solvent for the softenable material and said roller is rolledacross the surface of the layer of softenable material, therebysimultaneously developing the latently imaged member and removingresidual migration marking material and residual softenable material.